I have the Whitworths one
www.whitworths.com.au/o-b-bkt-ss-25hp-58kg on my TopHat, it carries an 8hp Tohatsu 4 stroke. You may need a rope attached to the ratchet bar to allow it to be pulled back, so you can lift/lower the motor. Hard to describe, but when you fit it you'll see what I mean. We bought the TopHat in 2009, the bracket was there then, and is still there, although recently the timber has started to deteriorate, so will need replacing. 14 years, is a good innings though. Don't forget to make sure you properly re-inforce the back of the surface you're mounting the bracket to. Ours is on the transom, with a full width board to spread the load of the four mounting bolts.